Is there any way of testing an unknown oil to see if it is made up on only Syntetic base (PAO) oil or mineral base oil?

FTIR will tell you if the oil is a hydrocarbon base or synthetic I believe.

Gas Chromatography, mass spec. or nuclear magnetic resonance testing both a pain to interpret and expensive.

FTIR, sadly will not determine the unknown base oils.

FTIR is useful to tell hydrocarbon (dino or PAO synthetic) from other lubricant base oil types like POE, PAG, alkylbenzene etc. As was said, FTIR will not tell PAO from dino basestocks.

Synthetic basestocks have no sulfur, so if you can factor out any sulfur from the additive package, you may be able to make a good guess based on that information. There are some very highly refined paraffinic basestocks that are virtually sulfur free as well, so this does not always apply.

Better late than never....
You can run viscosity @40 & 100 calculate the VI and assuming that the origional product was not a multi-grade you should be able to guess at a group 1/2 or 3 or 4 base stock. The other consideration is to heat the oil to a constant high tems say 150C and run continous TAN and see how quickly the product oxidises. Compare that to a group 2-3-4 and again you should be able to make a good guess.
Is all this fuss worth the effort??

regards.....

quote:

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Originally posted by mr. Hughes:
Is there any way of testing an unknown oil to see if it is made up on only Syntetic base (PAO) oil or mineral base oil?

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There is one way of finding if it is PAO or mineral ( even it is group III base ), that is with help of molecular weight and its distribution curve. PAO Mwt is narrow and mineral based mwt is wider. More information can be obtained from Mobil who market PAO
Kumar email kumartr2@yahoo.com

Your oil analysis lab will be able to tell you if it is a synthetic product by the VI of the base oil in the product.

Stavely Services
800-726-5400

They have an excellent staff and can answer most of your questions.

Hydrometer to check Specific gravity is the simplest way.

Sp Gr of common Flds

1. Solvents & fuels : 0.6 - 0.7 Aprox
2. Min oil (Lubes) : 0.79 - 0.89 Approx
3. Synthetic oils : Upwards of 1

M Hussam Adeni

quote:

Originally posted by Doug McBride:
FTIR will tell you if the oil is a hydrocarbon base or synthetic I believe.

I write from Italy, of my experienze if oil content few additive with FT IR it is possible, but if oil is is large additive FTIR can' t to resolve the question, there is much peaks !
sorry for my englisch

A simple way (if you have the right equipment) is to perform a elemental analysis(XRF)with focus on the Sulphur- content. Very low Sulphur level (around 0 ppm) can indicate that the oil is syntetic based.

The test of total sulfur is right if the is whitout additives, but in the case of motor oil where there is the barium sulfonate as detergent and disperdent it is not valid, same problem you have in the gear oil (sulfur is ep additive)

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For motor oil, you can have a simulated distallation run and compare amount off vs temperature. Synthetics will have narrow band where mineral oils have wide band. Most synthetics will have some degree of carrier oils in the additives and thus some interprtation is required.